Combined telephone and telegraph system



June 19, 1951 L. M. POTTS 2,557,392

- COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 15 Sheets-Sheet 2 FIG. 2 4

I2 FIG. 3

' INVENTOR LOUIS M. POTTS, DECEASED MARTHA W. C.POTTS, EXECUTRIX ATTORNEY June 19, 1951 I L. M. POTTS 2,557,392

COMBINED TELEPHONE AND TELEGRAPH SYSTEM 15 Sheets-Sheet 4 Filed March 17, 1947 56l FIG. l5 (DISTRICT SELECTOR) INVENTOR LOUIS M. POTTS, DECEASED MARTHA W. G. POTTS, EXECUTRIX June 19, 1951 M. POTTS 2,557,392

COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 15 Sheets-Sheet 5 FIG. 8

LOUIS M. POTTS, DECEASED MARTHA w. o. POTTS, EXECUTRIX 2 0 RN EY June 19, 1951 M. POTTS COMBINED TELEPHONE AND TELEGRAPH SYSTEM 15 Sheets-Sheet 6 Filed March 1'7, 1947 FIG. IOA

FIG. IO

INVENTOR l um aw AF- a M S.-

..T a S T N O m O T E M Mw M 3% U mm w.

June 19, 1951 L.- M. POTTS 2,557,392

COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 15 Sheets-Sheet 7 FIG. ll (SUBSCRIBER'S STATION) ATTORNEY.

June 19, 1951 Filed March 17, 1947 FIG. l2 (CALL REGISTER) 15 Sheets-Sheet 8 INVENTOR u I2 l3 LOUIS M. POTTS, DECEASED FIG. l4

ATTORNEY.

June 19, 1951 L. M. POTTS 2,557,392

COMBINEDTELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 I 15 Sheets-Sheet 9 FIG. l3 (CALL REGISTER) INVENTOR LOUIS M. POTTS, DECEASED BY MARTHA W. G. POTTS, EXEGUTRIX ATTORNEY.

June 19, 1951 M. POTTS 5 3 COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 15 Sheets-Sheet 10 FIG. l6 (INCOMING SELECTOR) 565 INVENTOR LOUIS M. POTTS, DECEASED MARTHA W. G. POTTS, EXECUTRIX BY 2 m TTORNEY June 19, 1951 L. M. POTTS 2,557,392

COMBINED TELEPHONE AND TELEGRAPH SYSTEM -Filed March 17, 1947 l5 Sheets-Sheet 11 FIG. I? (FINAL SELECTOR) SWITCH MAGNET FIG. FIG. FIG. FIG. FIG.

ll l5 l6 I? H \NVENTOR LOUIS M. POTTS, DECEASED MARTHA W. C. POTTS, EXEGUTRIX A TOR NB! June 19, 1951 L. M. POTTS 2,557,392

COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 15 Sheets-Sheet 12 FIG. l8

(LINE IDENTIFIER) INVENTOR LOUIS M. POTTS, DECEASED MARTHA W. o. POTTS, EXECUTRIX ATTQRNEY' IOOOV June 19, 1951 M. POTTS COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 15 Sheets-Sheet l3 Emir-2mm: M21: m QE INVENTOR LOUIS M. PoTTs, DECEASED MARTHA w. c. POTTS, EXECUTRIX BY Z1 7 ATTORNEY June 19, 1951 L. M. POTTS 2,557,392

COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 15 Sheets-Sheet 14 START IDLE IDLE

IDLE

IDLE

FIG. 2|

I lNVENTOR LOUIS M. POTTS, DECEASED MARTHA W. G. POTTS, EXECUTRIX BY Z1 ATTORNEY June 19, 1951 M. POTTS 2,557,392

COMBINED TELEPHONE AND TELEGRAPH SYSTEM Filed March 17, 1947 15 Sheets-Sheet 15 FIG.22

(LONG DISTANCE LINK) FIG. FIG. FIG. FIG. FIG. FIG. FIG. ll I5 22 22 I6 I? II FIG. FIG. l8 l9 FIG. 23

INVENTOR LOUIS M. POTTS, DECEASED MARTHA w. c. POTTS, ExEcuTmx zTTORNEY Patented June 19*, 1951 UNITED STATES PATENT OFFICE COMBINED TELEPHONEAND TELEGRAPH SYSTEM Louis M. Potts, deceased, lateof Evanston, Jll.,' by Martha W. C. Potts, executrix, Evanston, Ill., assignor t Teletype Gorp'oration, =Ohicag0,:Ill., acorporation of Delaware Application'jMarch 17, 1947, Serial No. 735,186

7 Claims. (015178 2) .1 This invention relates to communication .systems and more particularly'to systems combining telephone and telegraph operations.

A primary object of the invention is to provide a combined telephone and telegraph system wherein the calling subscriber may communicate with an unattended subscriber set and. leave a printed record of his message.

According to the present invention a communicationsystem is provided in which eachtelephone subscriber, in place of the telephone subset including a calling dial, has a subset in which the base includes a telegraph keyboard'transmitter and a type character recorder. The telegraph keyboard is used for setting up the connections for telephone service as W811 as for telegraph service and thus replaces'the dials. It also provides a'leave Word service. The subscriber automatically produces a printed record of all outgoin calls including exchange designation and subscriber's number. The system according to the:invention also includes a line identifier which automatically records on the calling station printer, the station designation and subscribers number of the connected station before a message can be transmitted.

More specifically, the subscribers unit of the presentinvention is intended-to replace'the present telephone vsubscribers unit and comprises a base which contains "the 'call bell, induction coil, and telegraph transmitting and receiving apparatus, and has a cradle to carry the handset, which includes the telephone transmitter and receiver. In place of the dial there is provided a keyboard which serves the purpose of the dial for controlling the switchboard at the 'central station'to set up a circuitto the'calledsubscriber for telephone or telegraph communication. For telephone communication the procedure is the sameas at the present time except thatw-hen the dialtone is received, the keyboard is operated in place of the dial.

At the central station, the apparatus of the telephone exchange may be the-same as at present, with two exceptions: First, to "the register circuit there is added a device which registers the called station designation'in a telegraph code and translates the telegraph code into'the regular decimal telephone code and registers it in that coda-which registration-controls the switchboard in the usual manner. Secondly, when telegraph service is'desired, there areadded to the link circuits, units which in 'response' to theoperation of the keyboard at either connectedsubscri-bers station send "to both subscribers stations positive and negative impulses, the number of which is determined by the-key depressed.

Since-most communications aretelephonic;and the telegraph apparatus will be required only occasionally, the circuitsof the system according to the present invention provide 1 only the number of telegraph repeaters required by the telegraph trafiicitself. However, to ,provide the greatest flexibility, the link circuits are ,provided with finding circuits so that a telegraph repeater can be attached instantly to any circuit when required. vIf this flexibility is sacrificed and the telegraph repeater is added .only in response .to a specialcall before connection is made, themodified circuits may besimplerior at least fewer, but the same in principle as hereinafter shown .and described. When the telephone communication is .used, the answering .party is usually readily identified, but in unattended ,or leave word telegraphservice, means must be provided to identify the connected station before the telegramis sent. Accordingly, a line identifier is included in the systemaccording to the present invention.

In the embodiment hereinafter described, the transmitter ,is of the ,revertive type. The only signal actually transmitted .from the .subscriberis station is a start impulse whichacts to start .a transmitter at thecentralstation, which attempts on each ,cycle of operationtotransmit alternately plus and minus impulses until a, total of six positive and five ,negativeimpulses have .beenconditiona'lly permitted. After .the number of each kind of impulse corresponding to the key dcpressed has been transmitted,.the circuitis opened at the substation for each kind of impulseso that, at the following attem S, the impulses of that polarity will not be transmitted. No timing of the impulses is required at the subscribers station and .nospeed control, except only that the impulses must belong enough and strong enough to Operate the magnet and the mechanism with certainty. When'two subscribers ar connect'ed, like code impulses .are transmitted .tolbOith stations simultaneously. Whichever line first .depresses a key seizes control .and determines the signals transmitted. Each transmittertransmits signals in both directions which maybe of a different character in the two directions to meet different circuit conditions, but similar to one another in the code arrangement of the elementary impulses; In the register circuit therepeated signals are used for registering the called station designation. fln the communication link circuit the second set of signals is used'to operate the recorder at the connected distant-station.

The system according to the 'present invention may be utilized in various ways. 'For example, thekeyboard may be used for callingpurposesjlik'e a "telephone died so that in telephonic conversation the procedure is exactly the same as atpresent. Ifthe called-partyf-ailsto answen-the-calling party may operate the keyboard, geta record of exchange and number of the connected station, and leave word as the printerat=the=called station is always controllable trom the keyboard at the calling station by :merely pressing the space bar. In telegraphic communication the keyboard may be used for calling in the manner of a telpehone dial and telegraph signaling may take place in either or both directions when the party answers. The record on the tape serves as a complete record of all the calls made, both telephonic and telegraphic. When a station is idle, the conditions are substantially the same as in the present substation set. Atall times, except when keys are depressed, all parts of the telegraph apparatus are at rest and no current flows through any of the substation telegraph apparatus.

In the usual impulse operated devices, impulses of current are alternated with no current intervals. In this apparatus, the intervals of no positive current are occupied by intervals of negative current. By this method, the equivalent frequency of the signals is one-half that of the usual method for the same total number of steps. The telephone calldial impulsing method uses intervals of current and no current. The maximum speed at which a subscribers dial may be operated for a seven unit station destination requires a minimum of about seven seconds and usually more. At the very moderate frequency of sixteen cycles the same call with this device will take three and one-half seconds. At sixteen cycles the telegraph speed is twenty words per minute. Double this speed or more than double seems entirely feasible. The transmitter shown here is one in which a maximum of six positive and five negative impulses are used, making a total of eleven impulses. The total number of intervals assigned to a character signal is sixteen intervals so that the idle intervals provide for printing and returning the parts to normal after printing, ready for the next signal. The start interval also provides some additional return time.

For a more complete understanding of the present invention reference is had to the following description taken in conjunction with the accompanying drawings wherein:

' Fig. 1 is a top view of the combined unit according to the present invention showing the keyboard and telephone units;

Fig. 2 is a plan view, partly in section, of the keyboard arrangement according to the invention;

Fig. 3 is a cross sectional view taken substantially on line 3-3 of Fig. 2;

' Fig. 4 is a sectional view taken substantially on line 44 of Fig. 2;

Fig. 5 is a front elevation of the unit according to the present invention showing the print hammer arrangement;

Fig. 6 is a front elevational view showing certain of the contact mechanisms;

Fig. 7 is a fragmental cross section showing the transmitter clutch mechanism;

Fig. 8 is a transverse cross sectional view showing certain control contacts and the telephone table mounting;

Fig. '9 is a sectional view showing the control mechanism and contacts controlling the axial motion of the type wheel;

Figs. 10 and 10A illustrate the codes used in the practice of the present invention;

Fig. 11 is a wiring diagram of a subscriber's substation;

Figs. 12 and 13 show diagrammatically the wiring of a call register;

Fig. 14 illustrates the manner in which Figs. 11, 12, and 13 are placed together to show how a .call is registered;

Fig. 15 is a circuit diagram of the district selector;

Fig. 16 is a circuit diagram of the incoming selector;

Fig. 17 is a circuit diagram of the final selector;

Figs. 18 and 19 represent the circuit diagram of a master identification signal generator;

Fig. 20 illustrates the manner in which Figs. 11, 15, 16, 1'7, 18, and 19 may be placed together to show a complete communication circuit between two connected subscribers;

Fig. 21 shows certain signal diagrams;

Fig. 22 shows a long distance link; and

Fig. 23 illustrates how Fig. 22 may be added to the arrangement of figures shown in Fig. 20.

Having reference to Figs. 1 to 4, inclusive, the combined unit according to the present invention comprises a housing II mounted on a base plate I2. Substantially level with the top surface of the housing II is arranged a plurality of key bars I3. Protruding through the key bars I3 and substantially level with the top surface thereof are a plurality of key tops I4. Positioned to the rear of the key bars I3 and key tops I4 on the housing II is a telephone cradle I5 (Fig. 1) adapted to support a telephone unit I6 of well known design.

At the front of the unit (Fig. 1) is a portion I! of lower level whereon the tape, after being printed upon by the type wheel printing mechanism I8, is adapted to be moved across. Referring particularly to Figs. 2, 3, and 4, the keyboard shown is of the coordinate type and comprises six horizontal bars I3 mounted on end brackets I9 pivotally supported on pivots 2 I.

Pivots 2| are carried on front and rear plates 22 and 23 supported vertically on the base plate I2. Bars I3 each have therein six equally spaced openings through which project the key tops I4. Key tops I4 are adapted to fit on vertical projections 24 of a series of bars 25 arranged transversely of bars I3. Bars 24 are slidably guided in suitable comb slots in side plates 26 and 21 mounted vertically on base plate I2, and each bar 24 is supported in a parallel motion manner on a pair of links 28 and 29 carried pivotally on pivot shafts 3| and 32, respectively. When a finger is placed on one of the key tops I4, some part of the finger will project over the edge of the opening through which the key tops protrude, and when the finger is moved downwardly, one of the bars I3 will swing around its pivot 2 I, and one of the bars 25 will also move downwardly with .parallel motion. It will be noted that suitable springs are provided for normally holding both sets of bars I3 and 25 in the positions shown in Figs. 2 and 3. It will be noted also that there are thirty-six combinations of two bars which may be depressed so that the keyboard will serve for the transmission of thirty-six character signals. There is also provided an extra bar 33 which, as explained in connection with the wiring diagram hereinafter, when depressed transmits only a start impulse and causes the record material to advance without effecting printing.

An alphabetical arrangement of characters is shown on the keyboard (Fig. 1) as following established telephone dial practice and best adapted to the use of the general public.

Figs. 10 and 10A illustrate the code employed in the practice of the present invention. Fig. 10 shows the signals used on the links which reach to the subscriber. Fig. 10A shows the signals used on intermediate links. In the case of the line identifier, the signals are as shown in Fig. 10A but thepositive (plus) signs indicate blocks of 1,000 cycle current, and zero indi-. cates no current. i

In the start interval, a minus current. is indicated. This, however, may not be a start impulse but may merely indicate the. battery for telephone communication. In the case of terminal links, the start impulse is an unbalanced condition of the line associated with the transmitting station. On the link associated with the called station there is no true start impulse, but. the alternating current print impulse conditions the printer for receiving and might be considered as replacing the start impulse. The so called start impulse is shown as unit length but it may be shorter as it can be terminated as soon as the transmitter at the central station starts; or, in fact, as soon as the supervisory relay locks up.

Positioned below the bars 25 is a universal bail 34 which is of a U-shape conformation and is adapted to be mounted pivotally on a shaft 35 supported or journaled in bearing bracket 35 integral with the side plate 26. Bail 34 is normally biased in a counterclockwise direction about its pivot shaft 35 bya spring 31. Integral with the bail 39 and extending vertically therefrom is an arm 38 to the extremity of which is pivotally connected a locking .bar 39. Bar 39 is slidably mounted in a slot in side plate 21. Bar 39 is provided with a series of sidewardly pro- J'ecting locking elements 4| (Fig. 2) which are adapted to cooperate with notches 42 provided therefor in each of the adjacent arms iii. The locking bail 39 is also adapted to cooperate with a corresponding series of notches 43 of bar'25 so that when a key is depressed the arm 38 of bail 34 is rocked in a clockwise direction, and a pawl or locking element 44 pivoted at 45 will rock counterclockwise locking the member 34 in its clockwise position, and in turn lock each of the plates l3 and bars 25 in their depressed position. The bars which have not been depressed are also looked in their normal position so that no other key can be depressed until the lock is released; that is, until the signal corresponding to the depressed bars has been transmitted.

Attached to each of the plates I3 is a pivoted depending finger 45, which will assume the dot and dash line position 41 (Fig. 3) when the key to which it is pivoted is depressed. Likewise, each of the slide bars 25 also carries a similar pivoted depending finger 48 which will occupy the dotted position 49 (Fig. 4) when the corresponding bar 25 is depressed. Fingers 46 pass through notches in a bar (Fig. 2) which is slidably carried in the side plates 26 and 21. In the plane of the depending members 46 there is positioned a slidable bar 52 which has on its lower edge a plurality of equally spaced teeth 53 adapted to be engaged by a pawl member 54 which is pivotally mounted at 55 on the armature 55 of a stepping magnet 51 carried on a bracket 58 mounted on the base plate I2. the drawings (Fig. 3) the armature 56 is shown attracted by the magnet 57, but when themachine according to the present invention is not in operation, the magnet 51 will be de-energized. When the magnet 5'! is energized, the armature 56 moves to its attracted or counterclockwise position about its pivot 59, and the pawl 54 will engage the first tooth 53. When the magnet 5'! is de-energized, a spring 9| will retract thearmature and advance the bar 52 rightwardly one step against the tension of its individual spring 62 (one end of which is attached to bar 52, as shown,

and the other end is attached to a spring post, not shown), and a holding pawl 60 will function to hold the bar 52 in its advanced position when the magnet is again energized for the next step. On the upper edge of the bar 52 is a series of projections 63 which are in the plane of the fingers as. Thus, as the bar 52 is moved alongrightwardly, step by step, some one of the projections 93 will eventually engage one of the depending fingers 59, which will be moved to the right along with the bar 52, and in so doing the bar 5| will also be moved to the right, and a contact 64 will interrupt the stepping impulses, as will hereinafter appear in connection with the description of the electrical circuit. The projections 63 are so spaced on the upper edge of bar 52 that for one of the bars 13 the bar 52 will advance only one step, and for another bar l3 the bar 52 'will advance six steps, and for other bars ii) the movement of 52 will be in intermediate amounts before the bar 51 is moved.

The right hand end of the bar 52 (as viewed in Fig. 3) is provided with a rack portion 95 which meshes with a pinion 66 which is rigidly mounted on a shaft 67. Fixed to the shaft 6'! is a collar 68 (Fig. 2) to the flange of which is fixed a pin 69 extending in a direction axially of the shaft 61*. Slidably carried on shaft 61 is a sleeve 1| which is provided at one end thereof with a flange 12 through a hole in which the pin 69 extends. On the opposite end of sleeve II is formed a type wheel 13 having six rows of type faces thereon, each row having six type faces engraved thereon. According to the motion of the bar 52 the type wheel will be positioned selectively in one of its six angular positions according to which one of the bars l3 has been depressed.

A stepping magnet 14 (Fig. 4) is provided with an armature 15 which carries a stepping pawl it. There is also provided a locking pawl 11 and a bar 79 which carries on its lower edge a series of teeth 19, similar to the parts already described in connection with the magnet 51. The bar '38 is moved in a similar manner by magnet l4 and the lugs 9i cooperate with the depending levers 48 and move a bar 82 to the left (as viewed in Fig. 4) to open a contact 83 after the magnet M has received a number of impulses corresponding to the one of the bars 25 which has been depressed. Attached to the bar 19 is a projection 89 (Fig. 2) which fits into a groove 85 in the sleeve H so that as the bar 18 is advanced step by step through the action of pawl 19 and teeth 19 on bar 18, the type wheel 13 is advanced in a similar manner to bring the proper row of type into printing position.

Mounted in the forward portion ll of the printing unit is a print magnet 86. Magnet 86 is an alternating current magnet and preferably has a laminated core and shaded poles. At twenty words per minute, magnet 89 will receive an impulse about three-tenths of a second long, and at forty words an impulse of three-twentieths of a second, so that it need not be fast except for a very short throw to operate the contacts. Commercial sixty cycle current is suitable.

Magnet 86 is normally energized, and following the receipt of the positive and negative impulses for each signal, the magnet 86 is de-energized and a print hammer 8'! is permited to rotate counterclockwise about its pivot point 88 under the tension of a printing spring 89. The hammerhead 9! then presses the tape 92 against the. selected type face of the type wheel 13. I Instead .of providing an ink ribbon or ink wheel, it

7 is proposed that a one time carbon ribbon will be fed in with the tape although either ribbon or ink wheel may be used if desired.

When the print hammer 81 approaches the end of its operating or printing stroke, a pin 93 thereon engages a lever 94 mounted on a shaft 95. Having reference to Fig. 3, an arm 96 is fixed to the shaft 95 so that as the shaft 95 rotates counterclockwise, the end of the arm or lever 96 functions to rotate the latching bell crank 44 clockwise thereby releasing the locking lever 34, and in turn unlocking the lever blade 43 to unlock the key levers I9, so that the plates I3 and the bars 25, which have been depressed, return to their normal position.

A feed roll 99 is rotatably carried on a shaft IOI appropriately journaled in the unit adjacent to the type wheel 13 (as Viewed in Fig. 5). Fixed to the feed roll 99 is a ratchet I02, and cooperating with the ratchet I02 is a pawl I03 carried on a lever arm I04 pivotally mounted on the shaft I I. The pawl I03 is normally biased by a spring I into engagement with the teeth on the ratchet wheel I02. A spring I06 normally biases the arm I04 in a clockwise direction to bring the arm I04 into normal bearing engagement with a pin I01 fixed to the printing arm 81. Thus, as the printing arm 81 is rocked in a counterclockwise direction by the spring 89, upon the de-energization of magnet 86, the pin I01 also rises with the lever 81 thereby permitting the spring I06 to rotate the lever arm I04, following the pin I01. By this action the pawl I03 is brought into engagement with the next tooth of the ratchet wheel I02 so that when the magnet 86 is again energized to rotate the lever 81 clockwise, the pin I01 urges the lever arm 04 counterclockwise about the pivot IM to thereby cause the pawl I03 to rotate the ratchet I02, and hence the feed roll 99, one step counterclockwise to advance the tape 92 (which is pressed between a pressure roller I08 mounted on a lever I09 urged by a spring III), to the left to bring a new printing area under the type wheel 93. The type wheel 13 has fixed rows of type and normally, when idle, no row is over the print hammer. When no negative impulses are transmitted, the type wheel does not rotate, and for word spacing the type wheel also makes no axial motion. Thus, for all printed characters one or more axial steps are made.

A lever arm II4 (Fig. 4) is also fixed to the shaft 95 and functions upon the counterclockwise rotation of shaft 95 to release the levers 16 and 11 from engagement with the teeth 19 on the bar 18, rotating the levers 16 and 11 against the action of their springs II5. Upon thus releasing the levers 16 and 11, the type wheel is permitted to return to its zero axial position, and the action of the arm 96 upon the latch 44 permits the type wheel to return to its zero angular position.

Having reference to Figs. 8 and 9 there is shown at the rear of the unit Ii a cradle I5 adapted to receive the handset I6 of well known construction. The handset I6 is connected to a cable H0. The cradle I5 is provided with a plunger II1 which cooperates with a lever I I8 to lock the keyboard. Lever I I8 is pivotally mounted on a pivot shaft H9 and cooperates at its free extremity with a pair of contacts I2I and I22. The lock latch 44 operates contacts I23 suitably mounted on the base plate I2. When the space bar 33 is operated the bevel on the depending lever arm I25, acts to move the bar 5I rightwardly (as viewed in Fig. 8) to open the contact 64. Moreover, the

8 depression of the space bar 33 through a bell crank lever I26 (Fig. 9) acts through bar 82 to open a contact I28.

The mechanism of the telegraphic parts of the subscribers set has been described hereinbefore. Certain parts which are included in the subscribers set, such as the call bell, induction coil and other electrical parts are not shown in the Figs. 1 to 9, but it will be understood that such parts are also mounted in the base of the unit.

Fig. 11 is a wiring diagram of a subscriber's station and of the subset, and the parts are shown diagrammatically in this View. Contacts I21, I28, and I29 are closed when the telephone headset I6 is in the cradle I5 and opens when the telephone headset I 6 is removed to make a call. When a key is depressed to make a call or send a telegraph signal, these contacts are again closed.

Having reference to Fig. 8 the contacts I21, I23, and I29 are controlled by a bell crank lever I3I pivotally supported on the shaft II9. Lever I3I is provided with a stud I32 adapted to cooperate with lever arm II8. Lever I3I also cooperates with the bail member 34. Thus, when the telephone I6 is lifted from the cradle I5, the spring I33 biases the lever I3I clockwise, and through pin I32 lifts lever arm II 8 to permit contacts I2I and I22 to close. Also, contacts I21, I28, and I29 are permitted to open. Thus, when a key is depressed, the bail 34 will be pivoted clockwise to, in turn, pivot the bell crank I3I counterclockwise to close contacts I 21, I20, and I29. Contact I21 preferably closes ahead of the others and short circuits the telephone receiver to cut out any sound from the telegraph signals. Contacts I28 and I 29 are also closed so as to prepare the circuit of the magnet 86 to receive the print or operating impulse. A relay I34 is provided with contacts I35, I36, and I31. In parallel with the winding of relay I34 is a rectifier I38. When the normal polarity of a telephone communication is on the line, the current flows through the rectifier I39 and relay I34 is not operated. When a signal is initiated at the distant subscribers station the polarity of the battery on the near subscribers line is reversed so that current now flows through relay I34 and not through the rectifier I38, and this relay now operates and by closing the above contacts prepares the receiver for a telegraph signal. The contacts I23 are closed when the keyboard lock latch 44 operates and they initiate the start impulse by unbalancing the line, as will appear hereinafter. This contact is operated from the latch 44 so as to assure that the key has been completely depressed and all portions of the apparatus properly prepared for the transmission of the signal. A rgeular call bell I39 is connected across the line through a condenser I4I.

When the magnet 86 operates, the following contacts are operated: Contact I42 opens to restore the line balance for the remainder of the code signal. Contact i43 opens to cut out the primary telephone circuits so that it will not shunt current from a magnet 51 and 14. Contact I44 is closed and connects code magnet 51 and 14 into the circuit ready to receive the code signal. Contact I45 closes and cuts out the telephone receiver. Contacts I46 and I41 close and hold the circuit for magnet 86 in operating condition after the relay I34 has released when the primary circuit of the telephone is open.

can register In the system. according to the. present invention. it is. essential. that the call be registered at the. central station. Since the telegraph. signal may be. transmitted at a. considerably higher rate of speedthansome exchange apparatus can operate,, and since the telegraph signals are of a different character fromthe switching signals, they must be translated. The so called panel system and the crossbar system both have call registers, and call registers may be added to. other. systems if it. is desirable to apply the arrangement according to the present invention to these. particular systems. It is assumed in the following description that the panel system is employed. Telegraph apparatus suitablefor the coordinate telegraph system. must be added. tothe. register as well as a translating. device. After. the signals have been; received, translated, and stored in this, condition, the remainder of the circuit may operate as. usual.

Having reference tQFigs. 11, 12,, and 13' (ar.- ranged as in Fig. 14),,the lines II and I52 from the subscriber's stationare connected to the ter minals I53 and i515. (Fig. 12). Associated with terminals I53. and I54 are. the sleeve and hunting terminals I55 and I55. There is also a line. relay I57 and a, cutoff relay I58v arranged as in well known central exchange oflices. except that there. is added to the. cutoff relay I58 a winding I59 and a contact IBI, used in connection with the. line identifier, described hereinafter. The; modifiedcall register. shown. in Figs. 12 and 13 is connected through a line. finder. and other. apparatus (not shown) and circuits. I62 to lines I5I and. I52 in a well known, manner.

In accordance with the present invention there is added to the call registershown in Fig. l2, a transmitter indicated generally as H33, which comprises a shaft I64 carrying a plurality of cams and forming the driven member of a clutch (not shown). The driving member'ofthe clutch is constantly rotating at a suitable speed ac-- cording to. the rate of signaling adopted. A stop. cam I65, whichris; rotatablewi'tlr the shaft I64, engages in the stop position thereof the. tip of a lever: I66 whichiorms the armature of a start magnet. IGI. A cam H58 also carried on. shaft: I'fiioperates' a pairof contacts I69 and? Hi to control various locking circuits. A- canr H2? mounted on shaft Its operates a contact I i-3* to apply alternating. potential to; the two sides of the loop in paralleL. from a transformer I14; the-primary of which is-fed-from'a 60 cycle-source for the purpose of operating the print hammer: and associated parts.

A series ofsix: cams M5 to- IBIl, inclusive, (Fig; 12) also carried on shaft 164, operate a series of contacts I 8i to I86 inclusive, respectively; Also mounted on the shaft I'M is a. series of five. cams iBI- to I95, inclusive, which operate a series of contacts I95 to 2%, inclusive, respectively. Cams H5 to I wand i9JI to I95; are so arranged that'the contacts IiH- of cam I are closed: just after the shaft N54 has started its rotation in the time. in.- terval assigned" tothe first positive impulse followed: by contacts I86", I182; IN, 183 83, i8 (etc, alternately) at the assignedzintervals. The first set of cams I15 to 580 correspond to positive impulses, and: the second set of cams Isi to I95. correspond to-negative' impulses which are transmitted alternately, one positive, thenanegative, etc. The contacts [81 to i867, inclusive, and to 2 30, inclusive; areconnected respectively to the operating'windingrof' a series of relays Z0"! to 2.! i,

10: inclusive. The other: terminals of the operating winding of relays 20] to: 20,6, inclusive, are connected over a conductor M2 to positive battery 2| 3. The other terminals of relays 251 to 2, inclusive, are connected over a conductor 2M to negative battery! [5. These relays 20'! to 2! I, in elusive, are provided with locking windings so connected thatas. eachrelay operates, it releases the precedingrelay of the same: plurality so that 1 no: more than one relay in each group may remaim operated when a complete signal has been received. For example, the locking winding for relay Zli extends. from. battery 213, over conductor 2:12,. through the locking windingof relay am, through; contact. 21:8; (now closed, assuming the relayz'il l tobe. energized) over conductor 2 I I, through contact, 2118,. over conductor 2l9, then through contact 22I (which is closed during most of the cycle'of" rotation of shaft I64) to ground. It will be observed that. contacts 222 and 223 of relays 232 and. 203, respectively, are similarly connected to. the conductor; 2l9. The operation ofi contact 221 willbe describedhereinafter.

There is also provided a step by step switch generally designated 22.4' (Fig. 13) which is operated in a step; by step manner by a stepping magnet 225, one step. between the signals for each consecutive digit of the station designation. Relays 291- to 2'III, inclusive, are also: provided with: additional contacts indicated generally as- 2-216 so interconnected that for each setting Qfjthfi relays; a: circuit will berpreparedi to the contact brush inthe-switch 22.4- which correspond to the telephone: decimal code unit represented by the Ten relays circuitis dismissed to await another call. Circuit 242: is a holding circuit for the relays 235 to 2.49;. inclusive, extending from battery 243,

through the winding of" operated ones of relays 235 to 240, inclusive, through contactz i if of said; relays: which have been closed, over conductor 2145,. then through circuit 242; to ground. Circuit 2162 is a holding. circuit in; the call registerwhich isigroundedwhen the'circuit'is seized and discon nected' from ground when the circuit is to bedismissed. COnta'ct'ZZI previously described, isoperated'bya cam. 24'6 which opens the contact 225' at the end of each signal after the setting of the relays 29.! to. 2 H; inclusive, have been transferred toone of the sets of'relays23I to 240, respectively. A cam 247: also secured to shaft I64 controls a contact. 248-1 which remains closed while each sig-- nali is being received to advance the sequence switch 224? over acircuit extending from ground, through contact 2&8 (when closed), over conprising Figs. 11; I5, 16,, 17,718, and 19, arranged as: shown. in. Fig. 20', and includes at least the calling station, a district selector, an incoming An eleventh arc: 2.41 (Fig; 13); of the switch serves to return the switch to its. initial position whenever the 

